1. Field of the Invention
The present invention relates to a method of depositing a film. More specifically, the present invention relates to method of depositing an oxide film or a nitride film.
2. Description of the Related Art
A manufacturing process of a semiconductor integrated circuit (IC) includes a process of depositing a thin film on a semiconductor wafer. In this process, improvement in evenness of a surface of a wafer is required in view of further microminiaturization of an IC. As a method of depositing a film to satisfy this requirement, a method of depositing the film called an atomic layer deposition (ALD) method or a molecular layer deposition (MLD) method is considered. According to the ALD method, a cycle, in which one (a reaction gas A) of reaction gases which mutually react is caused to adsorb on the surface of the wafer, and the adsorbing reaction gas A is reacted with the other one (a reaction gas B) of the reaction gases, is repeated to thereby deposit a thin film made of a reaction product on the surface of the wafer. Because the ALD method uses the adsorption of the reaction gas onto the surface of the wafer, the ALD method has an advantage that film thickness evenness and film thickness controllability are excellent.
A turntable-type film deposition apparatus is disclosed in Japanese Patent No. 4661990 as a film deposition apparatus performing the ALD method. This film deposition apparatus includes a turntable, which is rotatable and is positioned in a vacuum chamber, and on which a plurality of wafers are mounted, a separating area that is laid out above the turntable and separates a gas supplying area for the reaction gas A from a gas supplying area for the reaction gas B, evacuation ports corresponding to the gas supplying areas where the reaction gas A and the reaction gas B are supplied, and an evacuation device connected to these evacuation ports. In this film deposition apparatus, the wafers pass through the gas supplying area for the reaction gas A, the separating area, the gas supplying area for the reaction gas B, and the separating area along rotation of the turntable. With this, the reaction gas A adsorbs onto the surface of the wafer in the gas supplying area for the reaction gas A, and the reaction gas A reacts with the reaction gas B in the gas supplying area for the reaction gas B. Therefore, it is not necessary to change the reaction gas A to the reaction gas B while depositing the film, and the reaction gases A, and B can be continuously supplied. Therefore, there is an advantage that an evacuation/purge process is unnecessary thereby shorting a time period for depositing the film.
In a case where an oxide film containing a predetermined element is deposited using the above turn-table type film deposition apparatus, by using the reaction gas A being a reaction gas containing the above predetermined element such as a silicon gas containing silicon and the reaction gas B being an oxide gas such as ozone, an oxide film containing a predetermined element can be formed. In this case, a gas containing the predetermined element adsorbs firstly onto the surface of the wafer, an oxidation gas (the reaction gas B) is supplied onto the surface of the wafer, and the reaction gas A and the reaction gas B react thereby depositing a molecular layer containing the predetermined element. As described, the reaction gas containing the predetermined element adsorbs firstly onto the surface of the wafer and reacts with the oxidation gas on the surface of the wafer. Thus, the oxide film containing the predetermined element is deposited on the surface of the wafer.